If u had an video prooof then aap us baat pr ade rahjaoou r paying for a good phone so its ur right

There is option available in setting auto restart (search auto restart in setting)See whether the auto restart option is on or off ...if it is on then turn it off ....or otherwise go to service center and get ur work done

Phr toh phle aap service center jaoo with bill or issue bataoo or replace krwaloo

Visit service center of samsung and get it replaced free of cost if ur device is under warranty

Go watch ES TECHNO youtube channel you may find your solution even i tried and got solution as well .ES TECHNO samsung galaxy m series phone solutions